1. Field of the Invention
The present invention relates to optical systems. More particularly, this invention pertains to an optical system that is adapted to use in a camera of compact design.
2. Description of the Prior Art
Color cameras, particularly those of the full color "three-chip" type that employ three charge-coupled device (CCD) sensors that detect the three narrow band components of a full color image, find many uses. Socalled "linear" cameras that use linear CCD's commonly inspect items that are transported by conveyor belts. Linear full color cameras find particular utility in product inspection where product chromaticity provides a significant indication of quality.
Cameras of the above type require beamsplitter arrangements for separating the full color input into three primary color component images for application to the CCD's. Accordingly, a relatively large clear space or back focal length must be provided if one wishes to fit the required optics into a camera unit of useful compact size.
Present-day lens systems are limited in attaining a back focal length that exceeds the focal length of the lens. Accordingly, cameras of the above-described type have commonly employed relatively-long focal length lens systems. Such long focal length systems result in relatively-large and bulky camera assemblies.